1. Field of the Invention
The present invention relates to a light-emitting apparatus comprising a light-emitting device, which emits fluorescence or phosphoresce upon applying an electric field to the light-emitting device, including a pair of electrodes and a film containing an organic compound (hereinafter, an organic compound layer) interposed between the pair of electrodes, and to a method for manufacturing the light-emitting apparatus. In this specification, the light-emitting apparatus includes an image display apparatus, a light-emitting device, or a light source (including a lighting system). Also, the following modules are included in the light-emitting apparatus: a module attached with a connector such as an FPC (flexible printed circuit), a TAB (tape automated bonding) tape, or a TCP (tape carrier package); a module provided a PWB (printed wiring board) with a tip of the TAB tape or the TCP; and a module provided an IC (integrated circuit) directly with a light-emitting device by the COG (chip on glass).
2. Related Art
A light-emitting device using an organic compound as a luminous body, which is characterized by their thinness and light weight, fast response, and direct current low voltage driving, and so on, is expected to be applied to next-generation flat panel displays. Particularly, a light-emitting apparatus in which light-emitting devices are arranged in a matrix configuration are considered to be superior to the conventional liquid crystal display devices for their wide viewable angle and excellent visibility.
The luminescent mechanism of the light-emitting device is as follows: an electric field is applied to a pair of electrodes that sandwich an organic compound layer, and electrons injected from a cathode and holes injected from an anode are re-combined at the luminescent center of the organic compound layer to form molecular excitons, and then the molecular excitons revert to a ground state while radiating energy, consequently, luminescence radiation takes place in the organic compound layer. Known excitation states are an excited singlet state and an excited triplet state. The luminescence radiation is allowed to take place by reverting from either state to the ground state.
A light-emitting apparatus composed of a plurality of light-emitting devices being arranged in a matrix configuration may be operated by one of well-known driving systems such as a passive matrix drive and an active matrix drive. However, when a pixel density increases, it may be preferable to use an active matrix type system in which a switch is provided in every pixel (or every dot) because it can be driven at a low voltage.
A low-molecular organic material and a polymer organic material are studied as a material for forming a layer containing an organic compound that is almost a center of a light-emitting device. The polymer organic material is attracted more attention than the low-molecular organic material since the polymer organic material has higher usability and heat resistance than those of the low-molecular organic material. In addition, the layer containing an organic compound may be formed of a composite material made of the polymer organic material and an inorganic material.
The conventional active matrix light-emitting apparatus is manufactured to have the structure in which an electrode connected electrically to a TFT over a substrate is formed as an anode, a layer containing an organic compound is formed over the anode, a cathode is formed over the layer containing an organic compound, and light generated in the layer containing an organic compound is extracted through the anode, which is transparent to light, in the direction of the TFT.
However, in case of trying to improve resolution, there is a problem in that structure that an opening ratio is restricted by arrangement of a TFT, a wiring, or the like in a pixel portion.
Measures against the restriction of the opening ratio has been proposed that light emitted except in the direction of an opening portion is deflected and reflected, that is, the extraction efficiency of light generated in the layer containing an organic compound is improved (For example, see JP 2002-208491, and U.S. Pat. No. 6,091,195).
In view of the problems of an opening ratio and light extraction efficiency, it is effective to countermeasure against the problems by manufacturing an active matrix light-emitting apparatus having a top emission light-emitting device and having the structure to increase the amount of light extracted in the certain direction. Thus, it is effective to manufacture the structure by which light extraction efficiency is improved, while the restriction of the opening ratio being lightened.
The present invention is constituted by the structure in which a light-emitting device comprises a substrate having an insulating surface, a first electrode connected to a TFT, an insulator covering the edge of the first electrode, a layer containing an organic compound on the first electrode, and a second electrode on the layer containing an organic compound. The edge of the first electrode is formed to have an inclined plane toward a central portion of the first electrode. The inclined plane reflects light generated in the layer containing an organic compound. The inclined plane of the first electrode for reflecting light generated in the layer containing an organic compound is formed by etching a metal layer with a multiplayer structure, simultaneously with exposing a layer serving as an anode (or a cathode). At this time, an etching residue may be generated on the anode (or a cathode).
The etching residue causes defects such as poor coverage, or short-circuiting of the second electrode. Further, the etching residue affects adversely the reliability and the yields of final products a lot.